Meet Mark

Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...

Why Exercise Actually Does Matter for Weight Loss

If you follow health news, you might be thinking exercise doesn’t matter when you’re trying to lose weight. Vox just published a big piece showing how useless exercise alone is for weight loss. The NY Times says “eating less” is way more effective than “exercising more.” Obesity researchers like Gary Taubes and Yoni Freedhoff—who don’t agree on much else—both think using exercise to fix obesity is futile. I’ve always said that 80% of your body composition is determined by your diet, not how you exercise. And everyone knows it’s really hard, bordering on impossible, to out exercise a bad diet. You might be able to out exercise a bad diet if all you care about is abs and race times and make it your job, but eventually your poor health will catch up with you.

What is true? The value of exercise doesn’t depend on its caloric burn. The studies cited in the media pieces make it clear that energy expenditure through exercise has very little effect on weight loss. To focus on that and discard the effectiveness of exercise in general is misleading, though. And wrong, because fat loss isn’t just about mechanistically burning calories.

Notice what I wrote: fat loss.

We’re not trying to burn bone, or dissolve muscle, or shave a few pounds off our internal organs. All those things will reduce your weight but also your health, performance, and lifespan. We’re trying to burn fat. To take a couple notches off the belt. To look good naked. That’s what nearly everyone means when they say “lose weight.” So even if exercise doesn’t lead to a significant net loss of weight on its own, it can help us preferentially remove body fat while retaining lean mass.

So let’s see how exercise can help weight loss, both directly and indirectly. By the end of today’s post, you’ll be itching to go lift something or run really fast up a hill.

Exercise empties glycogen

If your glycogen stores are full, any extra carbs that aren’t immediately burned for energy will be shunted to your liver for conversion into fat, aka de novo lipogenesis. If you exercise hard enough to empty those glycogen stores, you’ve just cleared space for the carbs you eat. They’ll refill glycogen stores. Conversion into glycogen is a desirable metabolic fate for carbs. Carbs locked into muscle glycogen stores will not contribute toward fat stores. Instead, they’ll contribute toward high-intensity physical activity that aids fat loss.

Exercise improves blood glucose control

Although the scientific community debates the etiology of “hangry,” I think it usually stems from reactive hypoglycemia. Consider the sugar-burner whose blood sugar spikes after a meal then drops lower than it was before the meal. He won’t be able to access body fat for energy. His body wants the only kind of energy it knows—sugar—and it’s just not there. He’s going to eat something sugary and right away.

Now consider the fat-burning beast with low blood sugar. Is he going to freak out and binge because no energy’s available, or does he have the metabolic machinery necessary to take advantage of all that animal fat hanging around?

The best type of exercise that improves blood glucose control without inducing hypoglycemia in its own right is probably low-rep, high-weight strength training, walking, and short sprints (and I mean really short, like 5-8 second bursts).

Exercise improves sleep

Sleep is where fat loss actually occurs, because when you sleep, you experience the biggest spike in fat-mobilizing growth hormone. When you don’t sleep, cortisol increases to compensate for the groggy headspace and muddy thinking. Chronic levels of stress hormones, from chronic bad sleep, lead to fat retention, especially in the belly.

When you exercise can affect your sleep negatively, of course. Don’t train at 11 PM in a fluorescent light-lit gym with blaring pop music. Don’t settle for 5 hours a night because you want to wake up at 5:30 for a workout.

One cool thing about certain types of exercise is that it can make white adipose tissue behave more like brown adipose tissue. Hence, “beige.” It does this by reducing the size of fat cells, reducing the lipid content of said fat cells, and building more energy-consuming-and-ATP-producing mitochondria within the fat. Transplanting exercise-induced beige fat cells into sedentary controls improves their body-wide metabolic homeostasis and increases their muscles’ uptake of glycogen. This beigeing of white fat improves body-wide metabolic homeostasis and increases the uptake of glycogen by your muscles. It helps nutrients go where they’re useful.

(To make sure your exercise is working, remove a dime-sized pat of butt fat with a grapefruit spoon and observe the color. If it’s beige, you’re on the right track!)

(Please disregard the previous parenthetical.)

Exercise increases our resistance to stress

People respond to stress in many different ways. Some stay awake at night, endlessly ruminating on the hundreds of outstanding responsibilities. Some freeze up, unable to progress. Some go hungry, refusing even their typical favorite foods. But perhaps the most common response to psychosocial stress is binge eating junk food (PDF). This is especially common among women (PDF), who tend to focus on salty, sweet, and fatty snack foods. Stress eating is a major risk factor for weight gain; anything that reduces stress will probably increase fat loss.

Exercise blunts our stress response. When we’re physically fit, or we’ve just come off a tough 30 minute lifting session, stressors that’d fell a sedentary person just roll off the back. Training doesn’t just make our muscles stronger and our cardiovascular system more efficient. It trains our psyche, too.

Exercise makes movement fun again

It won’t always do this. But in my experience, when people get fitter, stronger, faster, and more confident in their own bodies, they enjoy their own bodies again. They start moving for the sake of moving. They’ll go for hikes because they enjoy it, not because they’re trying to work out. They’ll play sports again, and start walking when they would have driven. Movement becomes an integral part of their lifestyle. And once non-exercise activity thermogenesis—energy expenditure through daily movement, not formal exercise—increases, fat loss often follows.

Exercise increases your calorie sink

Exercise gives you a little wiggle room. It lets you eat enough to be satiated. It allows you to eat enough food to get the micronutrients you need. A full-on calorie restriction weight loss diet without exercise is rough; you must micromanage your entire day just to ensure you’re obtaining the vitamins and minerals your body needs while battling constant hunger. When you throw in exercise, you can eat a bit more. You don’t have to plug everything into a nutrition calculator. You can have an extra helping of potatoes to get more potassium, resistant starch, and magnesium. You can add another half cup of full fat yogurt with a blueberries to get your calcium and phytonutrients. Fat loss diets get easier when you train.

“Exercise” doesn’t tell us much, of course. There are many ways to exercise, and some are better than others for improving body composition and burning fat.

Much has been made of the studies showing that people training for a marathon fail to improve body comp. Over the course of 18 months of hardcore marathon training, males lost just 2.4 kg of fat and women didn’t lose any. That’s 18 months of pounding the pavement, and weight barely budged (and not at all in women). Everyone knows by now that endurance training isn’t great for body comp.

The overall most effective way for your average overweight to obese person starting from square one to lose fat and retain lean mass is resistance training combined with a low-carb Primal way of eating.

A recent study found that the most effective method for weight loss in the severely obese was diet+resistance training. Compared to endurance training+diet or endurance training combined with resistance training+diet, simply focusing on strength training and diet produced the best results for the severely obese. The most effective kind of strength training was whole body exercises using free weights. There was some evidence that if you wanted to add “cardio” training to your lifting, high-intensity interval training/sprinting was the only one that really worked. Typical endurance training was ineffective. This makes sense. It’s high-acute stress (your workouts are really tough but end quickly) and low-chronic stress (which few people, least of all sedentary obese people, are equipped to handle).

For people who are close to their ideal body composition but want to shed the last 10-12 pounds of body fat, sprinting has to be considered. This is the simplest (yet most intense) way to lean out those last few pounds.

For everyone else: lift, walk lots, and sprint if you’re able.

But honestly? Almost everything works. No matter what exercise modality you study, they’ll all generally improve your metabolic health, increase your muscles’ capacity for glycogen, increase your strength, improve whole-body glucose control, help you sleep better, and make your body fat a little more metabolically active. They can easily get out of hand—I’m looking at you, endurance athletes, 5-6x weekly CrossFitters—but nothing has to.

Combine your exercise with a Primal way of eating and you’ll be on your way to easy, sustainable fat loss. I’m biased, of course, but for good reason: this stuff works. A recent study of the paleo diet in middle aged type 2 diabetics found that while diet alone works (especially if it’s something like paleo) really well, it works even better when you throw in some exercise.

Over the course of 12 weeks, paleo diet-only subjects told to follow standard exercise recommendations (moderate cardio for 45 minutes to an hour three times a week) lost 5.7 kilos of body fat. Those who participated in supervised aerobic and resistance exercise lost 6.7 kilos.

Leptin, the pro-metabolism hormone that increases satiety and energy expenditure, dropped by 62% in the diet-only group. In the exercisers, leptin only dropped by 42%. Higher leptin means higher energy expenditure and lower appetite—both important for weight loss.

All in all, paleo dieters who exercised lost more body fat, retained more muscle, and had stronger metabolisms than those who didn’t. Sounds familiar, eh?

To sum up, training and diet work synergistically. You need both, and stalls in weight loss can often be countered by doing whichever one you aren’t. For most of you reading this, you’ve got the diet down pat. You’re eating well, you’re monitoring what you consume. But you might not be training. Today, right now, that stops. You have the tools you train effectively. You have the justification to train. You now know how imperative it is for your health, your performance, and, yes, your body fat levels that you move your body consistently.

Directly using exercise to incinerate calories and shift your energy balance isn’t sustainable. Eventually, you’ll burn out, or start bingeing on junk, or the health consequences will surpass the benefits.

Using smart exercise—lifting heavy things, running really fast once in awhile, running longer distances without lapsing into chronic cardio,walking, hiking, biking, climbing, playing, and generally just moving—to supplement a healthy diet is the only way to do it.

If exercise aids fat loss, it does so indirectly. It builds lean mass that consumes more energy and perpetuates more exercise. It clears glycogen stores, ensuring the carbs you do eat go to a good cause. It improves blood sugar control, limiting the peaks and valleys that cause many people to snack. It improves your mental health, self-confidence, and resistance to stress, deterring the types of destructive, depressive behaviors that often lead to binging and gorging and weight gain. It even seems to improve our sleep habits.

But it still does it.

What do you think, folks? What’s been your experience with exercise as a tool for fat loss? Has it worked? Has it not? Let me know down below!

Thanks for reading.

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55 thoughts on “Why Exercise Actually Does Matter for Weight Loss”

Wow, all great reasons to exercise and love the explanations of each. For me, it’s all about feeling good and having fun. I can’t say if exercise has helped with fat loss…I’ve managed to stay pretty lean while eating awesome food. My weight has stayed steady for years and I feel great. I eat primally and stay active…easy and fun!

The only exercise I seem to enjoy now days is push ups. However I’ve also read were a push up works almost every muscle in your body, so I guess it’s a great all around workout. At any rate I don’t have a weight problem, eating a primal”ish” diet(occasional grain consumption) and doing push ups keeps me in shape. I’ve always lived by the philosophy diet and healthy sleep are more important than exercise.

I can definitely attest to the stress and love of movement benefits. When I get into a good fitness routine, sleep and my general resilience to stress definitely improve. When I fall off the wagon, couch potatoe syndrome doesn’t do me any favors. Weight loss aside, a consistent exercise routine is worth it just for those two points.

All good stuff. And, of course, I’m sure some exercises (even indirectly) affect weight loss more than others. I’ll stick to my bodyweight exercises and sprinting as a one-two punch. I’ll be beige-ing up a storm.

Also, I’ve found that performing exercise in fasted states gives me some of the highest returns for fat loss. Since I consider myself pretty fat-adapted, if I pound out some quick, intense exercises toward the tail end of breaking my fast, I definitely feel like I get the most bang for my buck in terms of burning fat. If I want to build lean muscle, then I don’t exercise fasted, which is why I switch between the timing. It seems to work pretty well.

While reading this I just realized that although I used to have episodes of hypoglycemia I have not had a single one since cutting out grains. Even when I go longer without eating I just get hungry, not light-headed and shaky.

Walking works. After living paleo for over 4 years with no weight change in over 2 years and thinking I was as lean as I was going to get, I took a 10 day vacation and ended up walking more than double what I usually do and had a 24-hour stomach bug which forced more than my normal IF for a couple of days. I came back from vacation noticeably leaner, having lost 4 lbs. which have not come back several months after going back to my previous routine.

I’ve DEFINITELY noticed the indirect benefit of reduced hunger/cravings when I exercise. It’s pretty striking. You don’t realize how many false hunger cues you get throughout the day on the basis of stress and boredom. Glad I don’t practice eating 5-6 small meals/snacks a day like CW says anymore. I feel like that exacerbated the issue ten fold (training your body to constantly be seeking food). I eat the bulk of my calories in one or two sittings and practice PB style fitness. I’ve never had fewer false hunger cues (barring particularly stressful occasions).

Exercise absolutely helps me sleep better, and lowers my stress levels. I’m a ‘lie awake all night reliving every mistake I’ve ever made” kind of gal, so I NEED that exercise. Thankfully my dog has accepted her fate as my walking buddy, and YouTube has some really great Yoga videos. I can work up a pretty good sweat doing a 45 minute Vinyasa flow, and that features lots of bodyweight work. Add in a good horizontal sprint here and there, and my feel-good hormones are in high gear too.

For me, exercise got me off a plateau. I was 240 for quite some time and not exercising that much. Then I got into Orange Theory Fitness, probably around November, and started losing again. I’m at 217 now and that’s despite the summer crap food. (several birthday parties and camping/hiking trips)

Exercise was my missing key. Because I wanted to do something fun, I returned to Jazzercise. And I make the most of each routine, because now I know those “sprints” (running that makes me pant) and lifting heavy things (the biggest dumbbells I can hold) are better for me anyway. I knew I was eating a lot, too much for weight loss, for sure. I even stepped on the scale one day, expecting the worse. I was holding steady! Wow, after all the food I was eating? Then I also noticed that I was starting to see dents and shadows where my muscle tone was changing. In cool places. Like my abs and butt. I’ve been going routinely since January now and it’s starting to show. I love the social aspect of the class I attend, too. It’s a win-win. And yes, exercise may not be the whole picture, but it’s key.
And if I could actually remove a dime-sized pat of butt fat with a grapefruit spoon, I’d use a spatula and remove a lot more….

Can exercise over-ride sleep deprivation? I have a three-week old baby who wakes every three hours to nurse, have a potty break and nice snuggle with mommy. Ideally, when I first read about this happening two kids ago, I imagined I’d get three hours of sleep in between–kind of a nice baby-will-just-nurse-quietly-back-to-sleep and I’ll sleep too kind of thing. No, it’s a serious all-night job getting to morning in these early weeks. Wee one nurses, needs to burp, urps down my back, needs to pee, falls asleep for 20 minutes as I change my shirt and then once my head hits the pillow, I hear tell-tale poop-grunts happening and get up to change a mostly sleeping baby covered in mustardy poo.There went two hours and then I close my eyes to find it happening all over again moments later! I wish I could say I had nice sleep trained kids, but if the last two are any indication of what this will be like, I don’t think I started sleeping through the night until they were about a year old and that’s awful for weight loss! I just hang on to belly fat forever it seems. My diet is pretty clean, but I do find myself craving carbs to feel semi-human some days. I try to nap and for now I only walk a little (I definitely believe in rest and recovery–so I won’t start anything exciting until about 3 months postpartum). I don’t really need my old body back, but I read so much about how unhealthy it is to carry belly fat that I’d like to work towards that being in a healthier range.

In a word, no. Air, water, food, sleep … in that order for survival. 🙂

At this point in your life choose sleep over exercise IMHO. This will not last forever, it only seems like it will. Some walking, stretching, deep breathing would be good. As your life gets less insane then ease into extended walking, HIIT once a week and strength training twice a week.

Good–I am managing the air, water and food parts quite nicely! I aim to sleep mostly at night–I lost the ability to nap after having my first daughter. I think aiming for strength training twice a week might be manageable (using my 10-lb son as a baby weight!). We also live on a nice hill. I think I just need to be creative and not think of the gym as the only place to exercise. I often tease that the only way to get me to run is to set loose a lion, tiger (I should go to LSU) or other large, fast animal. I also do well with gym class instructors. But if I set out to run myself around the block, or lift weights, I get seriously unmotivated after about 5 minutes :-). Maybe we should get a fast dog that likes to run more than me! Yeah–three kids and a dog–just what we need! Good reminders to focus on the basics! And shower when possible!

Congratulations on your new baby! And I agree! Sleep you can come in don’t worry about exercise! It is busy having a newborn and two older kids. I have been there! I say just survive and be good to yourself!

My youngest is now 4 1/2, and life is much different then when my kids were newborn, three, and five years old. It won’t be like this for long! Just take care of yourself as you can, resting, eating, brushing your teeth, taking care of social needs, etc. And oh, I remember the luxury of taking a shower by myself, with the door closed! Exercise later, when it no longer competes with you or your kids basic needs.

Yep! Yep! Yep! I have been low carb no grain for years. I use to do endless cardio. It wasn’t until I resorted to body weight exercises that I saw the composition of my body change, which I love! Also few 5 second sprints a week!

“The best type of exercise that improves blood glucose control without inducing hypoglycemia in its own right is probably low-rep, high-weight strength training, walking, and short sprints (and I mean really short, like 5-8 second bursts).”

I don’t know how many times I’ve knocked myself and my blood sugar out going primal and over-exercising so to speak. It’s always been a very tricky balance to follow primal while maintaining a high level of exercise (or at least the level I want to maintain).

It’s almost as if we are meant to only exercise as much as it takes to deplete our glycogen stores, then stop after that before we induce hypoglycemia.

Thank you for this blog today. After my vacation was over the beginning of June I started my plan to loose about 8-10 pounds. I have been Paleo for about 5 years, I am 62 years old and found my blood pressure creeping up. I am below what I was when I left for vacation, now at 149#. How? I am using an App on my phone to keep track of what I eat, drink and exercise, and I am committed to waling at least 30 minutes 4 days a week. I work 12 hour shifts as a nurse 3 days a week. I do yoga classes 1-2 times a week. The weight is coming off at about 1# a week the last two weeks, so I will stick with this Paleo/walking plan as it seems to be working and I am happy. Timely articles like this one, are great to motivate to keep it up. Thank you.

This “debate” is a good example of the shortcomings of many kinds of experiments. Exercise “fails” for the same reason that many diets fail: most people don’t put in effort, whether it’s avoiding certain foods, or trying hard in the gym.

I think it’s silly to give contributing percentages, but it is more likely for someone to have a good physique with poor dietary habits and strong workout habits than with a good diet and no exercise.

Telling a group of people to exercise by jogging, walking, doing a cute little circuit at the gym, etc, won’t make it appear successful. There is a world of difference between them and those training to do a double bodyweight clean & jerk or run a 100m in the low 10s.

I would say that studies of protein intake are also affected by the “casual vs hardcore” subject issue.

I’ve recently started thinking about the diet / exercise combination this way: although your input (diet) affects 80% of your results, you still need to throw the right switches on the machine to get it running right. The exercise sets the necessary switches on the body / machine to burn fat. Perhaps these switches are epigenetic. I don’t know. You do need both.

I wonder about these “switches,” too. My diet has been the same for a year, and I track everything (weigh, measure, etc). I’m pretty precise about it. Running 20 mpw helped me drop about a pound a week. (Without exercise, my 1100-1200 calories per day had me lose, maybe, .25-.5 a week.) I also lifted weights and did yoga. If CICO were true, I would have disappeared and faded away long ago.

Four weeks ago,I started swimming and haven’t done anything else. I swim about an hour 4 xs a week and have lost 10 lbs this month. No changes in my eating. Again, the CICO math doesn’t add up.

In addition to the pounds lost, my sleep, which has always been pretty good, is now absolutely fantastic. Interesting to me how my body responds to one things but not something else.

Mark – If you haven’t read Jon Stanton’s (gnolls.org) article about metabolic flexibility, you should. He cites a lot of compelling research that indicates that exercise is key to maintaining our ability to switch back and forth between burning fat and sugar. Fits nicely into your overall thesis here.

I did a lot of cardio as a teen and young adult. I have some bad feelings about it because of the sheer waste of time it seems to have been, looking back. Honestly, I can’t imagine why any 16 year old would want to hop up and down for an hour a day, but it was the 80s & 90s and you had to be there…..I probably lost stem cells and who knows how many minerals… Adding animal foods, especially meat, I’m convinced is what has “made” me thin today, not exercise. I walk and do burpees for stress relief as much as anything else, and since I’m thin, I don’t worry about weight loss, since I’ve tended to lose too much weight, actually. But no long sweat sessions or workouts for me- never again.

I think another important reason to exercise when wanting to lose weight is body awareness and “inhabiting” your body more.
When I was fat, I didn’t like my body, it didn’t feel good and I lived mostly in my head. But then I lost a bunch of weight on the PB (thanks Mark!) and suddely my body was an inviting place to live again, without all those aches, pains and other vague complaints. When I started to do yoga, I learned how to be in my body. To feel where it is in space, to pay attention to whether or not something was good for my body, etc. Without that awareness, I may not have been able to stick to the diet or fine-tune it as well as I did. For example, I noticed that rice makes my muscles stiff, even though it doesn’t affect my gut much. So I mostly stopped eating that.
Now, I’ve been practicing Astanga Yoga for almost 3 years and I’ve not lost any more weight, but become leaner, more muscular, stronger, fitter, and I love my body more than I have ever done in my life 🙂

I think the term hypoglycemia is thrown around a little too loosely. Yes, it is real, but there are a lot of other things going on too. About the “hangry” phenomenon, I’ve actually tested my blood glucose many, many times when hangry and found the exact same pattern: I’m about 10 points higher than fasting (70’s to low 80’s fasting, high 80’s to mid 90’s when hangry). And if I eat a snack when hangry, my blood sugar will drop a few points after a few minutes. I don’t really know what it means, but I suspect a little bit of insulin resistance happening at that point. It’s not just about the amount of glucose in your blood, but how much is getting into the cells. I don’t have any other explanation for it. I have experienced many, many true hypoglycemia episodes in my life, and they are quite different from being hangry (both suck though). I have also had low blood sugar when I still felt ok (like a recent 53 reading during a potato hack. I was hungry, but didn’t feel bad otherwise). I’m guessing that in a situation like that, the hypoglycemia came on slowly, so my body didn’t flip out. My boyfriend is type 1 diabetic, and he is the least hungry of all when he’s seriously hypoglycemic (like 30!), yet he’ll sometimes think he’s really hungry when his blood sugar is in the high 200s. I wish I understood more.

Here is another release from Mark that he contradicts himself and throws out statements that he doesn’t back up with proof. The statement that exercise actually does matter for weight loss is a self-confirming title. Mark starts by stating that exercise assists with weight loss which I have not seen any research stating that it doesn’t. Over and over again he states that the diet has more to do with reducing fat in a person than exercise does. WOW, just what the research that he is refuting says. Then at the end of his article he states “If exercise aids fat loss, it does so indirectly.” So now Mark is saying that exercise does not help, but the byproduct of exercise is what helps. Make up your mind.

Then his statement about brown fat. Do adults have less brown fat than we did when we were infants? Or do we just have a lower percentage of brown fat to white fat and as we lose white fat our percentage of brown fat goes up?

What product or book is Mark going to try and sell from this article of his?

Another advantage of exercise over diet: It’s my understanding that exercise stimulates the production of cytokine-10 (AKA Interleukin 10 (IL-10)). This reduces inflammation in your body and promotes growth, and keeps you from decaying (thus, it keeps you “younger”). I think IL-10 also has cancer-fighting properties, but then I think that’s true of most anti-inflammatories. IL-10 isn’t generated by diet.

I find that it’s MUCH harder to cheat here and there on my eating when I’m working out regularly. 80/20 to 90/10 is easy when I’m working out because I tend to be more mindful of what I’m consuming when I work out regularly. It’s easy to undo a lot of hard work by eating junk. Also, adding exercise turns a diet into a lifestyle and when then happens I find me (and others) are more mindful of EVERYTHING else, like sleep and stress.

Love this article! It highlights all the advantages to SMART exercise but never deviates from the necessity for a proper diet! Again, this is an article I wish the media would share so we can stop all of this misinformation about exercise not being effective for weight loss and how it is effect for fat loss.

I have to admit, today, many people are giving up on exercise as a way to lose weight because they are not seeing the results they expect. But I like that this article helps explain why exercise still matters for weight loss, and why people should still make it a central part of their weight loss programs.